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11.
Caveolins modulate signaling pathways involved in cardiac development. Caveolin-1 exists in two isoforms: the beta-isoform derivates from an alternative translational start site that creates a protein truncated by 31 amino acids, mainly expressed in endothelial cells, whereas caveolin-3 is present in muscle cells. Our aim was to define caveolin distribution and expression during cardiac postnatal development using immunofluorescence and Western blotting. Caveolin-3 sarcolemmal labeling appeared as dotted lines from days 1 to 5 and as continuous lines after 14 days of age. Caveolin-3 expression, low at birth, increased (4-fold) to reach a maximum (P < 0.05) by day 5 and then decreased to stabilize in adults. Total caveolin-1 and its alpha-isoform were codistributed at birth in endothelial and smooth muscle cells; afterward, only the caveolin-1alpha labeling became limited to endothelium. Quantitative analysis indicated a similar temporal pattern of both total caveolin-1 and caveolin-1alpha expression, suggesting that caveolin-1alpha and -1beta are coregulated; the caveolin-1alpha levels increased fourfold by day 5 to reach a maximum by day 14 (P < 0.05). Tyrosine-14-caveolin-1 phosphorylation, low at birth, increased suddenly around day 14 (8-fold vs. day 1) and returning afterward to basal level. Because the T3/T4 level is maximal by day 14, caveolin-1 expression/phosphorylation profiles were analyzed in hypothyroid heart. The levels of caveolin-1alpha and consequently tyrosine-14-caveolin-1 phosphorylation, but not that of caveolin-3, decreased (50%) in hypothyroid 14-day-old rats. Our data demonstrate that, during postnatal cardiac growth, 1) caveolins are distinctly regulated, and 2) thyroid hormones are involved in caveolin-1alpha expression.  相似文献   
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Physiological studies have shown that the epidermal head and arm lines in cephalopods are a mechanoreceptive system that is similar to the fish and amphibian lateral lines (Budelmann BU, Bleckmann H. 1988. A lateral line analogue in cephalopods: Water waves generate microphonic potentials in the epidermal head lines of Sepia officinalis and Lolliguncula brevis. J. Comp. Physiol. A 164:1-5.); however, the biological significance of the epidermal lines remains unclear. To test whether cuttlefish show behavioural responses to local water movements, juvenile Sepia officinalis were exposed to local sinusoidal water movements of different frequencies (0.01-1000 Hz) produced by a vibrating sphere. Five behavioural responses were recorded: body pattern changing, moving, burrowing, orienting, and swimming. Cuttlefish responded to a wide range of frequencies (20-600 Hz), but not to all of the frequencies tested within that range. No habituation to repeated stimuli was seen. Results indicate that cuttlefish can detect local water movements (most likely with the epidermal head and arm lines) and are able to integrate that information into behavioural responses.  相似文献   
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Amino acid oxidases, which enantiospecifically catalyze the oxidative deamination of either D‐ or L‐amino acids, belong to the class of oxidoreductases functioning with a tightly bound cofactor. This cofactor favors industrial applications of D‐amino acid oxidases (D‐AAO). Hence, the enzyme is very important for the industrial application in the purification and determination of certain amino acids. In developing the enzyme‐catalyzed reaction for large‐scale production, modeling of the reaction kinetics plays an important role. Therefore, the subject of this study was the kinetics of the oxidative deamination, a very complex reaction system, which is catalyzed by D‐AAO from Arthrobacter protophormiae using its natural substrate D‐methionine and the aromatic amino acid 3,4‐dihydroxyphenyl‐D‐alanine (D‐DOPA). The kinetic parameters determined by the measurement of the initial rate and nonlinear regression were verified in batch reactor experiments by comparing calculated and experimental concentration‐time curves. It was found that the enzyme is highly specific towards D‐methionine (Km = 0.24 mM) and not as specific to D‐DOPA as a substrate (Km = 9.33 mM). The enzyme activity towards D‐methionine ( = 3.01 U/mL) was approx. seven times higher than towards D‐DOPA ( = 20.01 U/mL). The enzyme exhibited no activity towards L‐methionine and L‐DOPA. Batch and repetitive batch experiments were performed with both substrates in the presence and in the absence of catalase for hydrogen peroxide decomposition. Their comparison made it possible to conclude that hydrogen peroxide has no negative influence on the enzyme activity.  相似文献   
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Philippe Fossati 《PSN》2005,3(4):178-183
Functional brain imaging studies in healthy subjects suggest that several regions (prefrontal cortex, amygdala, thalamus, hippocampus, anterior cingulate) have specialized functions for emotional operations. Within these regions, the medial prefrontal cortex (MPFC) is considered to have a general role in emotional processing. Using a memory paradigm with verbal material, we recently demonstrated that the MPFC is specifically involved in self-related processing of emotional stimuli. Study with mood induction also suggest that personality traits may modulate the reactivity of the MPFC to emotional Stressors. Taken together these findings support the hypothesis that the MPFC subserve processes involved in emotion regulation. Dysfunction of the MPFC and related structures (i.e. amygdala) may increase the vulnerability to emotional disorders.  相似文献   
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Protein crystallization offers great potential in downstream processing of pharmaceutical protein active ingredients. The advantages, which are well known and widely utilized in low‐molecular weight crystallization, can also be expected to be found to some extent in protein crystallization. However, there is still a marked need for improvement in two main areas of protein processing, namely, in crystallization from impure solutions and scale‐up.  相似文献   
18.
The permeabilization and gene transfer phenomena in terms of the effect of electric field and cell parameters are reviewed in this paper. Electropermeabilization designates the use of short high‐voltage pulses to overcome the barrier of the cell membrane. A position‐dependent modulation of the membrane potential difference is induced, leading to a transient and reversible local membrane alteration. The electro‐induced permeabilization is long lived. A free exchange of hydrophilic molecules takes place across the membrane. The fraction of the cell surface which is competent for exchange is a function of the field intensity. The level of local exchange is strongly controlled by the pulse duration. This permeabilized state can be used to load cells with a variety of different molecules, either through simple diffusion in the case of small molecules, or through a multi‐step process as is the case for DNA transfer involving the electrophoretically driven association of the macromolecule with the destabilized membrane and its subsequent passage. Electropermeabilization is now in use for the delivery of a large variety of molecules: from ions to drugs, dyes, tracers, antibodies, oligonucleotides, RNA and DNA. While most studies are performed in vitro in cells in culture, an increasing number of data are obtained in vivo on tissues. However, membrane molecular and cell metabolic changes remain for the most part poorly understood. Therefore it is of great importance to elucidate the underlying phenomena both for the in vitro use of the method in terms of efficiency but also for the in vivo use of the method in terms of security.  相似文献   
19.
The genetic diversity of Cylindrospermopsis strains (cyanobacteria) was examined using mainly the 16S-23S internally transcribed spacer (ITS1) sequences. Strains were grouped in three clusters: (i) America, (ii) Europe, and (iii) Africa and Australia. These results suggested a recent spread of Cylindrospermopsis across the American and European continents from restricted warm refuge areas instead of exchanges between continents. On the other hand, they also suggested a recent colonization of Australia by African strains.  相似文献   
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